For many, many years I used an F3 with MD-4. I don't shoot sports, but I found it easier to keep my eye in the finder rather than taking it away to wind film. It is weighty, but I didn't mind it. This was before I discovered how tiny rangefinder cameras are.
I have an MD-3 for the F2, but I haven't been using it. I think the F2 is heavy and bulky enough on its own now. If I seriously start using the F2, I may use it. It has been serviced by Sover Wong, and has the brass gear instead of the always cracked nylon gear. So, it works perfectly.
I do like to use the Leica Motor M when photographing my kids. Same reason I had the MD-4 on the F3. Only issue is that a standard cable release will jam the shutter and film winding if you use it with the motor drive on. You have to cut the cable release tip so that it extends only between 6 and 7 mm.
For my IIIG, I do use the Leicavit all the time.